Optical module and method of assembling the optical module

Abstract

An optical module equipped with at least one optical component, a package for housing the one optical component, and a joining portion. The joining portion is formed within the package by Sn—Ag solder containing 2.0 to 5.0 wt % Ag and 2.0 to 20.0 wt % Au, or Sn—Zn solder containing 6.0 to 10.0 wt % Zn and 2.0 to 20.0 wt % Au.

1. An optical module comprising:
 at least one optical component;  
 a package for housing said at least one optical component; and  
 a joining portion formed within said package by Sn—Ag solder containing 2.0 to 5.0 wt % (weight-percent) Ag and further containing 2.0 to 20.0 wt % Au, or Sn—Zn solder containing 6.0 to 10.0 wt % Zn and further containing 2.0 to 20.0 wt % Au.  
 
   
   
     2. An optical module comprising:
 at least one optical component;  
 a thermo-control module for temperature-controlling said at least one optical component;  
 a package for housing said at least one optical component and said thermo-control module; and  
 a joining portion formed between said thermo-control module and said package, by Sn—Ag solder containing 2.0 to 5.0 wt % Ag and further containing 2.0 to 20.0 wt % Au, or Sn—Zn solder containing 6.0 to 10.0 wt % Zn and further containing 2.0 to 20.0 wt % Au.  
 
   
   
     3. An optical module comprising:
 at least one optical component;  
 a thermo-control module for temperature-controlling said at least one optical component;  
 a package for housing said at least one optical component and said thermo-control module; and  
 a joining portion formed between said thermo-control module and a base plate having said at least one optical component mounted thereon, by Sn—Bi solder containing 10.0 to 60.0 wt % Bi.  
 
   
   
     4. The optical module as set forth in  claim 1 , wherein said Sn—Ag solder further contains 1.0 to 3.0 wt % Cu. 
   
   
     5. The optical module as set forth in  claim 4 , wherein said Sn—Ag solder further contains 1.0 to 10.0 wt % Bi. 
   
   
     6. The optical module as set forth in  claim 1 , wherein said Sn—Zn solder further contains 1.0 to 5.0 wt % Bi. 
   
   
     7. The optical module as set forth in  claim 1 , wherein said at least one optical component includes a semiconductor laser. 
   
   
     8. The optical module as set forth in  claim 1 , wherein said joining portion is 5 to 100 μm in thickness. 
   
   
     9. The optical module as set forth in  claim 1 , wherein a difference in thickness between a front end (a 1 ) and rear end (a 2 ) of said joining portion in a direction parallel to a light emitting direction (A 1 -A 2 ) of said package is 90 μm or less, and/or a difference in thickness between one end (b 1 ) and the other end (b 2 ) of said joining portion in a direction (B 1 -B 2 ) perpendicular to said light emitting direction (A 1 -A 2 ) is 90 μm or less. 
   
   
     10. The optical module as set forth in  claim 1 , wherein said joining portion has a gold (Au) diffused portion where Au is dispersed in said solder, said Au diffused portion being formed by diffusing Au from a gold (Au) plated layer of 1 to 5 μm in thickness previously formed in at least either a surface of said package joining with said thermo-control module or a surface of said thermo-control module joining with said package. 
   
   
     11. The optical module as set forth in  claim 1 , wherein said Sn—Ag solder or Sn—Zn solder overflows from said joining portion between said thermo-control module and said package. 
   
   
     12. An optical-module assembling method comprising:
 a preparation step of preparing a thermo-control module that has a gold (Au) layer on one surface thereof and temperature-controls at least one optical component, and a package that has a gold (Au) layer of 1 to 5 μm in thickness on one surface thereof and houses said at least one optical component and said thermo-control module; and  
 a solder joining step of joining said one surface of said thermo-control module and/or said one surface of said package by causing Au to be contained from said Au layer into Sn—Ag solder containing Ag in a range of 2.0 to 5.0 wt %, or Sn—Zn solder containing Zn in a range of 6.0 to 10.0 wt %.  
 
   
   
     13. An optical-module assembling method comprising:
 a step of forming solder that joins a substrate of a thermo-control module and a bottom surface of a package, from a Sn—Ag alloy or a Sn—Zn alloy;  
 a step of forming solder that joins a bottom surface of a base plate having an LD chip and a lens mounted thereon and a top surface of said thermo-control module, from a Sn—Bi alloy;  
 a step of forming at least either a gold (Au) plated layer on the bottom surface of said base plate or a gold (Au) plated layer on the top surface of said thermo-control module to a thickness of 0.01 to 1 μm; and  
 a step of joining the bottom surface of said base plate and the top surface of said thermo-control module.  
 
   
   
     14. The assembling method as set forth in  claim 12 , wherein said solder joining step performs joining by employing Sn—Ag solder foil, said Sn—Ag solder foil being larger than said one surface of said thermo-control module and also being 5 to 100 μm in thickness. 
   
   
     15. The assembling method as set forth in  claim 14 , wherein said solder joining step further includes a pretreatment step of removing an oxidized film on a surface of said Sn—Ag solder, before joining is performed by employing said Sn—Ag solder foil. 
   
   
     16. The assembling method as set forth in  claim 12 , wherein said solder joining step previously coats said one surface of said thermo-control module with said Sn—Ag solder or said Sn—Zn solder. 
   
   
     17. The assembling method as set forth in  claim 12 , wherein said solder joining step includes a step of heating said Sn—Ag solder or said Sn—Zn solder so that the time it is melting is between 5 and 120 seconds. 
   
   
     18. The assembling method as set forth in  claim 17 , wherein said heating step presses said one surface of said package and said one surface of said thermo-control module against each other with a load of 3.0×10 4  Pa or less. 
   
   
     19. An optical module comprising:
 a carrier substrate mounting a semiconductor laser thereon;  
 a base plate mounting said carrier substrate thereon through a first joining solder portion;  
 a thermo-control module mounting said base plate thereon through a second joining solder portion, controlling temperature of said semiconductor laser, and comprising a Peltier element and upper and lower insulating substrates joined through a third joining solder portion; and  
 a package mounting said thermo-control module thereon through a fourth joining solder portion;  
 wherein T 1 ≧T 2 , T 3 ≧T 4 ≧T 2 , T 3 ≧240° C., and 280° C.≧T 4 ≧190° C.  
 
     where T 1 , T 2 , T 3 , and T 4  are the melting points of said first, second, third, and fourth solder portions, respectively. 
   
   
     20. The optical module as set forth in  claim 19 , wherein solder forming said third joining solder portion is composed of 80 wt % Au and 20 wt % Sn. 
   
   
     21. The optical module as set forth in  claim 19 , wherein solder forming said third joining solder portion is a Bi—Sb alloy. 
   
   
     22. The optical module as set forth in  claim 3 , wherein said at least one optical component includes a semiconductor laser. 
   
   
     23. The optical module as set forth in  claim 3 , wherein said joining portion is 5 to 100 μm in thickness. 
   
   
     24. The optical module as set forth in any one of  claim 3 , wherein a difference in thickness between a front end (a 1 ) and rear end (a 2 ) of said joining portion in a direction parallel to a light emitting direction (A 1 -A 2 ) of said package is 90 μm or less, and/or a difference in thickness between one end (b 1 ) and the other end (b 2 ) of said joining portion in a direction (B 1 -B 2 ) perpendicular to said light emitting direction (A 1 -A 2 ) is 90 μm or less. 
   
   
     25. The optical module as set forth in  claim 3 , wherein said joining portion has a gold (Au) diffused portion where Au is dispersed in said solder, said Au diffused portion being formed by diffusing Au from a gold (Au) plated layer of 1 to 5 μm in thickness previously formed in at least either a surface of said package joining with said thermo-control module or a surface of said thermo-control module joining with said package. 
   
   
     26. The optical module as set forth in  claim 3 , wherein said Sn—Ag solder or Sn—Zn solder overflows from said joining portion between said thermo-control module and said package. 
   
   
     27. The assembling method as set forth in  claim 13 , wherein said solder joining step includes a step of heating said Sn—Ag solder or said Sn—Zn solder so that the time it is melting is between 5 and 120 seconds. 
   
   
     28. The assembling method as set forth in  claim 27 , wherein said heating step presses said one surface of said package and said one surface of said thermo-control module against each other with a load of 3.0×10 4  Pa or less.